Hi, just bought a new Supra 21V with a boatmate trailer with the optional LED lighting package. Towed the boat on my girlfriend's 4Runner and didn't have any problems. However, I just bought a 2004 Range Rover HSE and had the dealer wire up the towing wiring harness. When I plug in the trailer (with either 7 to 4 or 7 to 5 pin adapter), I get some weird stuff. First, the blinkers in the truck pulse very rapidly (they don't normally do this). Second, the truck gives me an error on the dash that says "Check Trailer Wiring". Third, even with the truck off and the lights off but the wiring connected up, the running lights on the trailer pulse faintly. Very weird.

I took the truck in this morning to the dealer and they checked the wiring and assure me that everything is correct. Boatmate tells me they haven't heard of any problems with Range Rovers.

Yeah, I agree that the Range Rover is the problem, but they are telling me everything checks out - they even tried a trailer that they had at the dealer with no problems. It has to be something with the LEDs I'm guessing. Need to tell them what to look for.

I have a cayenne and it does not work correctly with led trailer lights. The reason is that since the voltage for leds is lower the computer thinks the lights are out. This may be the. same problem with the range since they are both european and rely alot on computers

I think Manny has it. I work for a class 8 truck manuf. and we use a light control module which measures the resistance at or from each bulb. If you install led's there is so little resistance that the computer thinks the bulb is blown and will throw a code. Likely something similar on your deal, we have a parameter to turn off this functionality so you can run led's. Not sure if Rover does the same deal or not.

The resistance on led's is much higher then normal lightbulbs. Perhaps that is why it's saying check the trailer lights. Also the voltage is the same, but not the amperage. It's much lower on the led system. It has sometime to do with this. Let the dealer find out if the system works with LED systems

That seems to be the concensus, from everyone here and from the trailer manufacturer and the Rover dealer. I'm going to take the boat in with the truck to have them fix it. Wish the trailer manufacturer would build that type of stuff into the trailer, especially when they know that problems can occur on many vehicles. I'll post the solution once I find it. Thanks for the help.

Tom I thought the resistance would be lower on the LEDs. The reason I say this is because I have see in other fourms people with the same problem when they install or replace the stock tail or turn lamps with LED bulbs. They were saying the flasher can not feel or sence the LEDs because of the Lower not Higher resistance. The fix was to install a flasher that could sence the lower resistance bulbs

"Most of the newer vehicles use ground sensing over resistance to know when to trigger. Bypassing all of that is nice for the owner (you wont have to buy schematics and such) when it is possible. What I would guess is that Range Rover uses a similar system and the addition of the trailer lights to the common ground for the lighting board is creating enough load on the ground to make the lighting board think the switch is engaged. What happens if you let the trailer lights ground through the ball/frame and remove it (ground) from the harness? Might try it with a test light to see. This may work as the overall load on the common ground to the lighting board will not be increased, but there will be enough current to power the lights, as that is the current wire being used. Of course this all hinges on RRs setup of lighting. They may be using some super secret squirrel stuff I have never seen."

You will likely need to install a resistor pack on the lights so the RR will not think there is a bulb out. You can buy them here.

____________________ Turn signal issues with LED bulbs LED brake/tail lamps will not flash with thermal flasher units due to their extremely low current draw. These installations will require an electronic flasher unit, available in our car bulb shopping category (for some vehicles) or at your auto parts store. Try to find flashers designed to work with LED bulbs, they will say "LED compatible". Often HEAVY DUTY flashers will also work with LED bulbs.

We offer some LED Flashers in our Tail/Brake Turn Signal Bulb category but we do not know which one (if any) will fit your vehicle. You will have to compare the pin-out of your flasher with the pin-outs of the flashers we offer, to see if we have a match, BEFORE you order one. Sorry but we do not have a flasher application list or the expertise to tell you which of our flashers will fit your vehicle.

Another fix is the installation of Load Resistors which are wired across (in parallel with) the turn signal bulbs to simulate the load of a standard filament bulb. We also have these available in our car bulb shopping category.

Dash indicators reporting burnt out bulbs LED bulbs may cause some newer vehicles to indicate a bulb is burnt out (because of their low power consumption). Some cars indicate this by increasing the flash rate of the turn signals, some turn on a bad bulb indicator. The only fix for this is to install Load Resistors across the bulbs that are being indicated as bad. Some vehicles will also disable the cruise control system if a brake light bulb is being indicated as bad, the installation of Load Resistors will also solve this problem. _______________________________________